High-voltage method and system



Dec. 26, 1950 M. NEWMAN 2,535,651

HIGH-VOLTAGE METHOD AND SYSTEM Filed May 12, 1945 '7 Sheets-Sheet 1 Fla. 3

Dec. 26, 1950 Filed May 12, 1945 M. NEWMAN HIGH-VOLTAGE METHOD AND SYSTEM 7 Sheets-Sheet 2 I N V EN TOR. Maze/s NEWMAN BYPM do ATTOEN E K;-

Dec. 26, 1950 M. NEWMAN HIGH-VOLTAGE METHOD AND SYSTEM 7 Sheets-Sheet 3 Filed May 12, 1945 A7- TGRNE K:

Dec. 26, 1950 M. NEWMAN HIGH-VOLTAGE METHOD AND SYSTEM 7 Sheets-Sheet 4 Filed May 12. 1945 /Nl/ENTO/? Mame/s NE WMAN ATTo /vEKs Dec. 26, 1950 M. NEWMAN 2,535,651

HIGH-VOLTAGE METHOD AND SYSTEM Filed May 12, 1945 '7 Sheets-Sheet 5 S7 33 l 6O INVENTQR M0? E78 NE w/v/Arv.

ATTQRNE vs.

Dec. 26, 1950 M. NEWMAN 2,535,651

HIGH-VOLTAGE METHOD AND SYSTEM Filed May 12, 1945 7 Sheets-Sheet 6 3 so 5! s9 44 E 6 52 57 O 3 2 I .1 [60 r 3 53 't 30 E 73 33 5 275 Dec. 26, 1950 M. NEWMAN 2, 5,65

HIGH-VOLTAGE METHOD AND SYSTEM Filed May 12, 1945 '7 Sheets-Sheet 'T V I NVEN TOR: MORRIS NEWMAN.

ATTORNEYS Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE HIGH-VOLTAGE METHOD AND SYSTEM Morris Newman, St. Paul, Minn.

Application May 12, 1945, Serial No. 593,516

2 Claims. 1

This invention relates to methods and apparatus for providing high voltage unidirectional and high or intermediate frequency power supply for installations wherein the load is relatively small and where voltage control is of importance. Heretofore, it has been customary to provide heavy apparatus for even low wattage installations and to use heavy transformers, rectifiers, filters, and the like.

It is an object of the invention to provide methods and apparatus for supplying high voltage either unidirectional or at a high or intermediate frequency or a combination of the two, and to provide systems and methods wherein close output control is achieved. It is a further object of the invention to provide low weight and low cost apparatus for the foregoing purposes such that the apparatus will be conveniently portable by hand, or where weight is a, major consideration, as in aircraft installations.

Other objects are inherent in the apparatus and methods hereinafter illustrated, described and claimed.

The invention is illustrated by the drawing in which:

Figures 1, 1a, 4, '7 and 10 are circuit diagrams of four principal modifications of the invention; Figure 1a corresponds to Figure 1 but shows slight variations in the wiring;

Figures 2 and 3 are, respectively, a plan view and side elevational view of the apparatus, the Wiring diagram of which is shown in Figure 1;

Figures 5 and 6 are, respectively, the plan and side elevational views of the apparatus shown in the wiring diagram, Figure 4;

Figures 8 and 9 are, respectively, the plan and side elevational views of the apparatus shown in the wiring diagram, Figure 7;

Figure 10 is a modified form of the invention;

Figures 11 and 11a are each a fragmentary part of the wiring diagrams shown in Figures 1, 7 and 10 showing a modified form of voltage control connection; Fig. 11a corresponds to Figure 11 but shows slight variations in the wiring;

Figures 12, 13, 14, 15, 16, 17, 18, 19 and 20 are wiring diagrams of control systems which are alternates to those used in Figures 1, 4, '7 and 10. The method of the present invention may be carried out in several forms of apparatus and involves utilizing a low voltage alternating current source of power supply which is transformed or otherwise converted to a somewhat higher direct or alternating current potential which in turn serves as the input of an oscillator tube.

The oscillator tube is adjusted to oscillate at i any desired frequency in the range from intermediate audio frequencies to intermediate or high radio frequencies. The output of the oscillator tube is applied to the primary of a transformer which is designed to handle the chosen frequency. Thus, for frequencies ranging from the intermediate audio frequencies up to the low radio frequencies, an open or closed core, iron cored transformer, capable of operating efficiently in the frequency range stated, is used; whereas, in the higher radio frequencies an aircore transformer is utilized, providing a high voltage secondary. On the transformer, there is produced a corresponding high voltage output which is utilized directly as the output, or this may be rectified, or the output may be a combination of a high unidirectional voltage with an alternating current component of the oscillator tube frequency.

Figures 1, 2 and 3 illustrate a system in which the apparatus below the bracket [0 serves to convert the relatively low voltage, low frequency alternating current supply to a direct current at a somewhat higher voltage. In this form of the invention, this is accomplished by means of a voltage doubler tube generally designated I I having a pair of cathodes l2 and 13 which are in directly heated by series connected heaters l4 and i5. Cathode l2 cooperates with anode I6 and cathode l3 cooperates with anode l1. Alternating current, for example, volts or 220 volts of a commercial frequency, is supplied to feeders L1 and L2. Feeder L1 may be grounded as indicated at l8, if desired. From junction 20 on L2 there extends a branch 2| leading directly to anode M3, L2 being extended and connected directly to cathode 13. From cathode I2, line 22 extends to junction 25 which serves as one of the out ut terminals of the voltage doubler apparatus I0. From anode ll, line 23 extends to terminal 3!) which likewise serves as one of the output terminals of the voltage doubler apparatus I U. A pair of condensers 26 and 27 are connected in series between terminals 25 and 30, by a circuit extending through lines 28, 29 and 3!. Junction 44 on line 29 is an intermediate voltage terminal and is connected by line 43 to junction 6 on optionally grounded feeder L1. I

The unidirectional potential existing across terminals 25 and 3! in the apparatus just described, is two times the crest value of the alternating current supplied across feeders L1 and L2 at no load, and serves as the input to an oscillator tube generally designated 35, which may be a three-element tube, but is preferably a multiple grid tube or a five-element tube such as that illustrated.

In a preferred form of the invention illustrated in Figure 1, the oscillator tube 355 is provided with a cathode 35 which is indirectly heated by heater 3?; the tube also has a control grid 38, a screen grid 39, and a suppressor grid M3. The tube also includes an anode ll. At lfi there is illustrated a transformer having a primary winding' lfi, ,a high voltage secondary winding ii, a low voltage secondary winding 38. An iron core 49, which may be an open or closed iron core made of thin transformer core stock is used when the frequency is within the range'suitable for such use, as heretofore mentioned. (Otherwise the core is air. At 59 there is illustrated a half-wave rectifier tube having=cathode 5-1 which is indirectly heated by heater 52 and which also has an anode 53.

The filaments of tubes H, 35 and 56 are energized in any suitable manner, preferably byconnecting in series, through a circuit extending from L1, through heater 52, connection 42, through heater 3'8, line 34, heaters M and 15, line [9 and resistance 24 to junction 5 on L2. Where tubes of standard manufacture are used, the resistance 24 is preferably included for adjusting the cur- "rent to an amount suitable forthe filaments, but where tubes of especial filament voltage are rnan- -ufactured the resistor 2- 5 may be omitted.

The circuit connections between oscillator tube 35, transformer 45, and rectifier 5%} are as follows: Fro-mjunction on feeder L1, a circuit extends over'line E3 to junction M on line 29, and thence to the screen grid 39 of the tube From junction line 32 extends to the cathode 5| of rectifier Eli, and from junction 33 on line 32 circuit 54 extends to cathode '36 and suppressor grid 40 of oscillator tube 35. From junction 33 there also extends a circuit through line "5' 1 to junction 55 and thence through the regulasting-resistance 55 and condenser 5i, inpar-allel, to terminalfiil, which serves as one of the output terminals of the apparatus to which output line *(ii is connected.

'Terminal 59 is connected tol'ine "32 :(or junction '30 or"33) and serves as another-one of the output terminals or" the apparatus. One end of the transformer secondary winding 38 is-likewise connected to terminals iill, the other end of winding 48 being connected through line 62 and through :grid'bias resistor and grid bias condenser 65, 'in parallel, 'tothe control grid 3%. Terminal 2?) is connected'through line 6? tooneend of primary winding d6 of the transformer 45, the other terminal of winding it being connected through'line 88 to anode ii of'the oscillator tube '35. If desired, an adjustable condenser "59 may be connected across the primary winding A l as shown in Figure 1a to :control the frequency of oscilla- :tion=.of oscillator tube .35, but in many instances this is unnecessary because of the .inherent capacitance of the circuits provides all the capaci- 'tivereactance needed for the oscillating circuit .ofztube'iifi. Anodei53 of the-rectifierfiil is con- ;nectedby line H to tap-l2 on the :highvoltage secondary winding ll of the transformer --,4,5,-tap i2 being preferablymade adjustable. erminal 13 ofthe high-Voltage-secondary windingifi'l serves as one oftheoutput terminals of the apparatus, output line rbeing connected thereto. 'T-ap 1S ,onisecondary ,winding .47, also preferably adjustable, serves likewisefas anoutput terminalof the :a par tusto whichoutput line 18 is connected.

in the appara us .of F u e the winding 98 may be disconnected from terminal 60 and connected via line 48 to line 32. When this is done terminal 60 is connected via line G3 to the intermediate voltage tap 44. This type of connection is shown in Figure 1a.

If a device having a corona discharge function is connected between terminals 6i and 73, as illustrated at 290-49! in Figures 11 and 11a, and elsewhere in ,the drawings, then ,a very closely .controlledoutput voltage ,is obtainable, gthat has a number of advantages over the usual unregu- Jated or indifferently regulated high voltage supply. The corona discharge element 29El--29l may be simply an element in the load device, or it may be a separate corona discharge element that is used simply for its regulating function. As a result :the power supply has many useful applications. The apparatus of the present invention has particular advantages as a power supply for dust precipitation apparatus where corona discharge of limited amount is utilized for ionizing :thedust prior to precipitation. The control function of this power supply is described here- *inafter.

The first :control function is that the power supply delivers a voltage output that is nearly independent of variations in the supply line volt-' zage,.-over a wide range of line voltage variations.

In any corona discharge, there is practically'no flow of corona current for voltages below a certain minimum value which is determinedby the shape and configuration of the corona discharge surface, the .gas surrounding the surface, the conditions of pressure, temperature and the :presence of any types of radiation that might produce ionization. At this certain minimum voltage, current in :the form of corona discharge willbegin to "flow and for each small increment of voltage increase, th increase in corona current will be large. In other words-up to this certam-minimum voltage (hereinafter referred to as the -minimum ionizing voltage), the corona discharge device presented an almost infinite re- ;sistance, but When'theminimum ionizing voltage is reached the resistance drops from this almost infinite value and continues to drop rapidly for 'each succeeding increment of voltage increase. Accordingly, when a corona discharge device is connected between terminalsfil and 18 and {the tap it is adjusted until the voltage between 6| and "1B is just slightly above the minimum ioniziing voltage, then small changes in outputvoltage will produce unexpectedly large changes in the output current that-fiows between terminals 6! and 18. Hence, if the power supply is adjusted so that ionization in the corona discharge device has just begun or is about to begin and the line voltage applied between terminals L1 and L2 is increased, a corresponding variation of nearlyiequal proportions takes placein the .voltage output of the voltage doubler and tends to produce a corresponding proportional variation in :the voltage output of the oscillator tube 35. This tends to increase the-voltage output of the high voltage transformer 45, 'an'dthus thevoltage applied to the corona discharge device. A given percentage increase in voltage across the corona discharge deviceproduces a much greater percentage variation in the corona current and this change in corona currentproduces a change in voltage drop in "the control resistor 55. Control resistor 56 is connected in such a manner that an increase in ionizing current flow "producesan increased "negative bias on the oscillar in time .3 this tendin to reduce the out voltage of the oscillator tube 35. Thus an increase in line voltage while tending to increase the voltage output between terminals 6| and I8 (and also Bl to 15, 15 to 18 and 59 to 15 or 78) has also a control exercised by virtue of the corona discharg device and its effect upon the oscillator tube 35 so that for a given percent variation in line voltage the actual variation in output voltage can be held to a very small fraction of that percentage.

Likewise, voltage changes that are due to changes in the efficiencies of the voltage doubler, oscillator, output transformer, or rectifier will also to some extent be compensated by the control exercised by the corona discharge device 29029l, regulating resistor 55 and the condenser 51.

Some control of output voltage is provided even if the loads across SI and 15 or 18 or across 59 and 15 or 18 are constant resistance loads. However, the control is very much more effective if one of the loads is a corona discharge devic operating at a voltage a little above its minimum ionizing voltage.

The second control function that the power supply provides is a control over the current supplied from terminals GI and I and from terminals GI and 78. This control function may be described as follows: It may be assumed that a corona discharge device is connected between terminals GI and 18 and a more nearly constant resistance load is connected between terminals BI and 15. An exemplary installation of this type is the modern dust precipitators wher the precipitator plates are connected between 5| and and the ionizing surfaces are connected to 5| and 78. If the value of the resistance between terminal SI and 15 is decreased (as by short circuit in the plates of the precilpitator), there will be a. tendency for the current into this load to increase. This will increas the current flow in the control resistor 56, and hence will increase the voltage drop across this control resistor 55. This increase in voltage drop across the control resistor 56 gives the oscillator tube an increased negative bias and this tends to reduce the voltage output of the oscillator, which in turn tends to reduce the voltage available at the output terminals BI and 15. Thus, a decrease in resistance of the load between terminals BI and 15 has the net effect that the current output will increase somewhat but the ratio of the increased current to the original current will not be as great as the ratio of the original load resistance to the de creased load resistance, which would be true were control not exercised. The system thus produces a controlled current output.

The control functions just described are those that would result if no corona discharge device were connected between terminals SI and 18. However, if a corona discharge device is also connected between terminals El and '18, then the above described control is modified. Thus, where there is a simple decrease in the value of the load resistance between terminals 61 and 15, it was shown that this decrease tends to decrease the output voltage. If a corona device is connected and is in a corona emitting condition, such a decrease in output voltage would produce a relatively big decrease in the current flow through the corona discharge device, and hence a relatively big decrease in the voltage drop in the control resistor 56. Such a decreased drop in the control resistor is supplementary to the tendency first described. The general results of 6 these two tendencies may be summed up as follows: (1) If the corona discharge device is made the dominating element in the circuit then the output voltage will remain reasonably constant in spite of variations in load resistance between terminals 6| and 15. (2) If the control exercised by the load current from terminals GI and 15 is made the dominant control then the output is substantially a controlled current output. The question as to which of the circuit elements is the dominant one depends on many factors such as the relative value of the current in GI and 15 compared with the current in El and 18, and upon the characteristics of the corona discharge device, such as its configuration, the voltage applied to it, atmospheric conditions, whether the corona discharge device is in a chamber, the conditions of the gas, etc.

Figure 12.-The corona discharge device may be made the only control element by connecting the variable load as shown in Figure 12. In this modification the constant resistance load is connected between terminals 59 and 15, while the corona discharge device is connected between terminals GI and 18. In this modification transformer winding 48, resistor 64 and condenser 65 are omitted, and grid 38 is connected directly to terminal Bil. When the connections are made as shown in Figure 12, the load current from 59 and 15 does not pass through the control resistor 56, and as a result no control is exercised by variations in this load. Hence, the current from 59 to 15 is free to vary as the reciprocal of the resistance of the load, the only limitation being that for a power supply of given design, the current available has a certain maximum as determined by the overall regulation of the unit. The corona discharge device such as 290--29| of Figure 11 would be connected between GI and 78 (Figure 12) and therefore act to maintain the terminal voltage between 59 and 75, at a constant value. This arrangement is especially useful where a voltage output i required that does not vary in spite of variations in line voltage or load conditions. The corona discharge device may be kept at constant conditions of pressure, temperature, etc. and for this purpose may be housed in a closed tube, not illustrated.

If the gas surrounding the corona discharge device is allowed to vary in temperature or pressure, then the voltage output is a function of the temperature or gas pressure, and where such relatively slight variations are not disadvantageous, the corona discharge device may be exposed or physically (but not hermetically) enclosed.

There has been described above the various ways in which the current output from terminals 5! and 15 may be controlled, including the extreme case of no control over current when the load is drawn from terminals 59 and 15. There is, in addition to the above types of control, a valuable type of control exercised over the current through the corona discharge device itself. If it is assumed that the corona discharge device is connected between terminals 6! and E8 of Figures 1, 11, or 12, then variations in resistance of the corona discharge device result in control which will tend to keep the current in the corona discharge device constant. The amount of voltage variation required to accomplish this is dependent on the size and configuration of the corona discharge device. By properly selecting or designing the corona discharge device thevolt- 7 age between terminals 6! and 7501' 59 and 1-5 can be made to vary in avariety of ways as a function of the atmospheric conditions in the corona discharge device.

From the foregoing discussion, it can be seen that this power supply has several advantages over the usual power supply consisting of a transformer, rectifier and filter.

By connecting apparatus of Figure 1 as shown in Figure 11 with a corona discharge device 299-29! between terminals SI and T8, and the load connected across lines 53 and T5, the voltage output is relatively independent of both variations in supply line voltage and variations in the resistance of the load. If the corona discharge device 29l-29l is contained within a sealed tube so the pressure of the gas within the tube is a function of temperature only, then the power supply can be used to produce an output voltage that is a function of the temperature only. If the corona discharge device 290-491 is in a sealed tube and is held at a constant temperature by a suitable thermostatically controlled heater, not illustrated, then the power supply provides an output that is independent of variations in atmospheric conditions (temperature and pressure), as well as independent of variations in line voltage and load resistance. The arrangement just described is an ideal power supply for a cathode ray oscilloscope.

When the corona discharge device such as 29i329-l, Figure 11, is open to the atmosphere,

the voltage output between terminals 6! and 78 is controlled so that the corona current is relat'ively constant and as a result the amount of ozone produced by the corona discharge device will remain relatively constant in spite of changes in atmospheric condition '(such as changes in pressure) and in spite of changes in line voltage and at the same time the voltage between 55 and lit likewise varies as a function of the voltage between 3i and 78. Such an arrangement is ideal for supplying power to a precipitator consisting of an ionizing wire for ionizing dust, bacteria, pollen, etc. and a set of precipitating plates for removing such ionized particles from the air. In such a case the ionizing wire is connected between 5! and T8 and the precipitating plates connected between 5! and T5. The ionizing wire of the precipitating apparatus may be made of slightly larger size than wire 2% so as not to ionize quite as much as 298 for a given voltage. Wire 2'96 therefore acts as the control wire; Such a precipitator when supplied with power from a power supply such as the one here described would tend to regulate the amount of ozone and nitrogen oxides produced so that the atmosphere produced is safe to breathe regardless of how atmospheric conditions and line voltage vary.

A third advantage or this type of power supply is that. it provides certain safety features. In the first place, when loads are connected between terminals 5! and 75 or between SI and 18, this power supply has a controlled. current output, as previously explained. By suitably select ng the sizes of the circuit elements the maximum current output under any conditions can be limited so that it is below a value that would possibly cause injury or death to a person. The power supply lik-ew'se provides a smooth unidirectional output without requiring high capacity condensers to filter the output. The reason for this is that when the frequency of the oscillator maybe reasonably high, for example" in the range of 8 medium audio frequencies tolo w radio frequencies', and the capacity required at such frequencies to filter the output to a smooth unidirectional output is very small compared with that required for filtering the output of a rectifier operated on conventional low frequency (50-60 cycle) power supply systems. When used with dust precipitation systems the precipitating plates themselves are sufiici'ent to serve as the filter capacity. Since the filtering capacities required for the type of power supply h'ereindescribed are very small, the energy stored can be within safety limits even with the voltage across the fil'ter condenser at a high value. In addition the type of power supply herein described is safer than conventional types used in precipitator apparatus because the chances of overheating because of poor operating conditions are very slightcompared with the conventional type consisting of transformer, rectifier, and filter. For example, the output terminals 61 and 15 or BI and 1 8 may be shorted without producing" any overheating, due to the control efiected by grid 38. A coin ventional power supply under similar conditions would badly overheat the rectifier tube and the transformer.

Since the degree of regulation provided in the power supply inherently prevents overheating, it can operate under any load conditions Without interrupting service by the blowing out. of fuses or tripping of overload relays or circuit breakers as is the case with conventional power supply systems when overloaded. In addition the power supply more convenient to operate because nor mal operating conditions are restored as soon as normal load conditions are re-established. This fact makes this power supply particularly adapt able to providing power to a precipitating unit wherein the output circuit is subject to hazards of foreign substances shorting the output circuits (ionizing chamber and precipitating plates). When so used, when a short occurs service is immediately re-established when the precipitating plates and the ionizing chamber are cleaned or the short clears itself.

The power supply also offers the advantage that many types of output are ava'lable. Between terminals T5 and '18 there is available a high voltage of any desired frequency from high audio fre quen-cies to radio frequencies depending upon the frequency of oscillat'on of tube 35; this voltage may be controlled in any of the manners previously described. There is available between terminals 6! and T5 and between terminals GI and '38 an uni-directional high voltage output ether pulsating or steady; these voltages may also be controlled in any of the manners previously decribed. Between terminals 59- and F5 'or between 59 and 18 there is available unidirectonal voltages either pulsating or steady, these voltages again controlled in any of the manners previously described. A combination of unidreotional voltage and intermediate to high frequency voltage is available between terminals 6| and 15 if between terminals 6! and 13 there is connected a capac'tive load of sufiici'ent capacity so that the impedance is low to the frequency generated by the oscillator. The relative values of theuni directional and intermediate to high frequency components may be selected by varying the position of taps Hand 18. Again these voltages'may be controlled by any of the schemes previously outlined.

A further, very material advantage of this type of power supplyis the'small space occupied by the unit as described later in the text of this application.

In the foregoing descriptions the power supply has been described in which certain valuable results are achieved by controlling the output voltage of a vacuum tube oscillator by controlling the bias voltage of the oscillator tube. All of these valuable results may be obtained by using any of several alternate systems of controlling the output voltage instead of the bias control system just described in detail. Such alternate systems are shown in Figures 1, 12-20. The systems shown in Figures 12-20 all have a number of points in common, which may be described here and then not repeated as each system is described. Each has available a source of direct current suitable for supplying voltage and current to the plate circuit of the oscillator or an amplifier tube. In Figure 1 this is the apparatus under the bracket [6. The positive terminal of this seurce is designated as and the negative terminal is designated as 36. Another source of direct current of somewhat lower voltage and suitable for supplyingvoltage and current to a screen grid of an oscillator or amplifier or to the screen grid or plate of some tube requiring less voltage than available between 25 and 3!), has its positive terminal designated as 44 and its negative terminal (in common with the plate supply voltage). In each of the alternative systems shown in Figures 12-20, these power supply terminals are shown merely as lines 30, 44 and 25, top to bottom. Each alternate control system has a high voltage output transformer generally designated as 45, suitable for the frequency of oscillations generated. Where the frequencies are suitable for the use of an iron core, one is used as shown at 49. At high frequencies this is omitted. The primary winding is designated as 46 and the high voltage secondary winding as 41. The high voltage winding has a tap labeled 12 which is connected to the anode 53 of the high voltage rectifier 50, which has a cathode 5| heated by heater 52. The cathode 5! is connected to junction 33 which is connected to control resistor 56 with condenser 57 in parallel. Output terminal 59 is connected to junction 33. The other end of control resistor 56 is connected to junction 60. High voltage output line 6i is also connected to junction 60. A variable tap 16 on the hig-h voltage secondary winding furnishes the connection to line 18, another output terminal of the high voltage supply. The end of the high voltage secondary winding designated '13 is connected to line 15, another high voltage output terminal. sponding numbered elements in the device of Figures 1 and 11.

Each of these alternate control systems may be substituted for the grid bias control shown in Figure 1 by disconnecting the apparatus on the right hand side of Figure l (i. e. the apparatus under bracket 80) from terminals 25, 44 and 36 and connecting in its place the corresponding lines of the apparatus described by any of the alternate control systems, Figures 12-20. The heaters of the tubes shown in the control system are, as a matter of convenience, not shown as connected to any voltage supply although, of course, a suitable connection must be made so that each tube is supplied with a suitable current along with the tube or tubes, such as voltage doubler tube I! of Figure 1, included in the direct current supply for plate and screen voltage. In all of the alternate systems the voltage appear- These elements correspond to corre- 5-."

" to the cathode 36.

10 ing between junctions 33 and 60 is used as the controlling voltage.

Figure 12.--In the apparatus of Figure 12 the oscillator tube 35 has its anode 41 connected to one end of the transformer primary 46, the other end of 46 being connected to positive supply line 25. The plate circuit may include a condenser 69 in parallel with 46 for tuning or this may be omitted where the capacitance of winding 46 suffices. The control voltage appearing across the resistor 56 is placed in the control grid circuit by connecting 33 to the cathode 36 and 66 to the control grid 38. The screen grid 36 is connected to the intermediate positive voltage supply line 44. The suppressor grid 49 is connected to the cathode 36. This system oscillates by virtue of the feed back obtained through the capacitance of the high voltage transformer. The output is controlled by the grid 38 becoming more negative on increased output, and less negative on decreased output.

Figure 13.-In this modification oscillator tube 35 has its anode 4i connected to the primary 46, the other end of the primary being connected to 25. The control voltage across resistor 56 is placed in the screen grid circuit by connecting junction 66 to the screen grid 39 and junction 33 to line 44. The cathode 36 is connected to 30. The control grid 36 is connected to grid leak 64 and grid leak condenser 65 in parallel, the other end of 64 being then connected to one end of a low voltage secondary winding 43 of transformer 45. The other end of winding 48 is connected to negative line 33. The suppressor grid 46 is connected In Figure 13 there is illustrated an inductive feed back oscillator wherein control of the output voltage is obtained by varying the potential of the screen grid 39. The higher the output voltage (and load current), the less positive screen grid 33 becomes and the less the output the g-reater becomes the positive potential of the screen grid 39.

Figure 14.-In this system the oscillator tube 35 has its anode 4| connected to 46; the other end of 46 being connected to 25. Variable condenser 69 may be used if desired. The cathode 36 is connected to negative supply line 36 and the suppressor grid is connected to the cathode. The control grid 38 is connected through resistor 64 and condenser 65 in parallel, and thence a low voltage secondary 48 0f transformer 45, the other end of 48 being connected to negative supply line 30. The screen grid 39 is connected to 44. This oscillator tube 35 has a fourth grid 39a suitable for controlling the effectiveness of the control grid in producing variations in the plate current. The more negative 39a becomes the smaller is the variation of the plate current for a given variation in the control grid potential. Also, the less negative 39a is made, the greater is the variation of plate current produced by a given variation of the control grid potential. The control voltage across resistor 56 is connected into this fourth grid circuit 36a by connecting junction 33 to the cathode 36 (negative line 36) and by connecting junction 66 to the fourth grid 39a. As the voltage and load circuit increases grid 39a becomes more negative and visa versa, thereby effecting output control.

Figure 15.This circuit is identical with that shown in Figure 13 except that the variable screen voltage is not obtained directly from the voltage across the control resistor 56 but as an amplification of this control resistor voltage. To accomplish this, junction 33 is connected to the ace-ace;

11 cathode 303 of a high mu amplifier tube 30.0, and junction 60 is connected to the grid 35.2. The cathode 333 is also connected to the screen grid 39 of tube 35. The anode 38! is connected to. in-

termediate positive line 44 and a filter condenser 305 is connected between cathode 333 and anod 35L Increased voltage output of the power supply system results in increased current flow in resistor 56. The resultant increased potential drop across resistor 56 results in grid 302 becoming more negative and this results in increased resistance between cathode 383 and anode 35 1, thus providing a lower positive potential for the screen grid 39 and hence lower output voltage from oscillator tube 35. Thus a control over output is exercised.

Figure 16.In this modification an oscillating system is formed by the cathode 35, the control grid 38 and the screen grid 39 of pentode 35,. These three elements form. part of an oscillating circuit by virtue of the fact that the grid circuit is coupled to the screen grid circuit through transformer 550. The control grid 38 is connected through the grid condenser 4M and grid leak 45.5. in parallel, and thence through coil 402 of'transformer 401'}. to negative line 30. The

screen grid 39 is connected through coil Mil to the intermediate. voltage supply line 44. Coils 4M. and 562 are inductively coupled as indicated in Figure 16. andform. a transformer generally designated as 455 which may include an iron core 483 in the event the frequency of oscillation of tube. 35 is suitable for such a core, otherwise an air core transformer is used. A capacitance 406,

as indicated by the dotted lines, may be used if needed. The oscillating current flowing from cathode 35. to screen grid 39 induces an oscillating current of the same frequency in the anode circuit of the pentode 35, if the plate circuit is tuned so as to have approximately the same resonant frequency. The plate circuit is formed by connecting the anode 4| through the coil efi to theterminal 25., The amplitude oi the alternatingcurrent in coil: l -,6.- mayv bere ulated by adjusting the-potential of, the third grid 43. This system is arranged. so that as. the output current through resistor 56 increases, the third grid 43 becomes more. negative with respect tothecathode 35. This. is accomplishedby connecting grid lfi-to junction 6-5 and cathode 35,to junction 33.

Figure 17.,'Ihis system is the same asthe system described inFigure. 16 except that in Figure 177. thethird griddilispositive withrespect to the cathode 35. and control of the output. voltage is obtainedby making the grid 40 more or less positive with respect to cathode, 3B. This is accorn; plished y amplify ng thecontrohvoltage appear: ing across resistor. 56 before this voltage is impressed on grid 45. To accomplish this, junction 33 is connected to grid 302 of amplifier tube 395 and. junction 60 is connected.v to cathode 353;. Anode. 3.0!, is-connected, to the, third. grid 45 of pentode 3.5. The intermediate positive voltage supply line. 4.41. of the plate supply, is connected through dropping resistor 38.6 to, anode 3,51 and negativeline. is connected to cathode353g. A filter-condenser. 3.05.is connected between anode 353 and cathode 353. To illustrate how thiscontrol functions, assume that. pentode. 35 is oscillating and that an output is. being supplied to loadsbetweenbl; and 7.8. and iii and 15. This.

produces a. drop in resistor. 55. which establishes the grid potential for amplifier tube 3.5!], which in turn establishes, the resistance between. anode 3 and cathode3fi3. Thus, the potential'oi grid 12 411 with respect to cathode 3'5 is determined by the current flowing from 44 through 365 and the amplifier tube 305, Now, if it is assumed that the load current in 55 increases, then grid 382 becomes more positive with respect to 303 This decreases the resistance between and 303, which in turn allows more current to fiow from 44 through 356 and amplifier tube 3 05. Hence the potential drop across resistor 356 is greater and the drop across tube 305 less. Thus, as the output increases the control system functions to make less positive with respect to 36 and hence decreases the output of the oscillator tube 35. Conversely, a decrease in output cur rent fiowing in resistor 56 produces an increase in the output of oscillator tube 35.

Figure 18.This system is the same as that shown by Figure 16 except that the controlled output of oscillator 35 is amplified before being supplied to the primary 35 of the output transformer 55. The output of the oscillator 35 is applied to the primary of an intermediate transformer 386, whose secondary 355 is tuned by condenser 3;!5. The voltage across the secondary 358' is applied to the grid circuit of -amplifier tube 3.15.5: by connecting one terminal of 358 to cathode 353 and the other terminal to grid 352. When using a screen grid; amplifier as shown, the screen grid is connected to; a. positive source of supply Ma of the plate supply system, whose voltage is at some suitable point between the values of the voltages available at terminals -ld and 25. This voltage, ad may be used to supply plate current to the oscillatortube 3 5 asshown. The plate circuit ofthe; amplifier-355 is completed: by connecting the platesupply terminal 25 to one terminal or". the high voltage output transformer primary 5% and the other terminal of the primary to the anode 35! of amplifier 3-90. The cathode 3 33 is connected to negative supply line 35. A condenser isused; if needed, to tune the primary winding 45. This system is suitable for handling larger amounts of output power, than any of those systems previ ously described. An extra choke coil 3!! and a filter condensers |2-areconnected so asto maintain the screen grid voltage. of 355; very stable and thus. eliminate any possibility of 355 oscillating at some frequency of its own rather than simply amplifying the output of oscillator 35.

Figure 1-9.Tln's system issomewhat similar to that shown in Figure 18. in that electron tube 3-15 is a triode arranged to operate as. a self. excitedioscillator. Thegridcircuit includes a grid condenser 55. anda gridleak resistor 55 inzpara allel, and also a. secondarywinding 358A on transformer 335. The cathode 55 is connected to the negative plate supply line The plate circuit of is. formed by connectingthe anode M o e terminal. r ary. indin .5.9, on transformer .335, the other terminal of 359 being connected to the positive plate supply line 34. The output of this self excited oscillator 35 thus showing in primary winding 3% induces a corresponding voltage in the secondary winding 358-: Secondary 3538 is tuned by the condenser 3M. One terminal of secondary winding 358 is connected to control grid 352 of amplifier and the other is connect d to the anode of 553i of a control tube 555. The cathode of tube 555 is connectedtot-he negative supply line 35. The res lt of these connections is that the grid 3512.; of amplifier 3535 has applied to it an alternating current voltage of constant amplitude from the oscillator tube 35 and an unidirectional potential.

13 equal to the voltage drop between anode M and cathode 503 of control tube 500. The screen grid 305 of 300 is held at constant potential by virtue of the connection to positive plate line 44 through a filter consisting of the series inductance 5i! and the shunt condenser 3|2. The plate circuit of tube 300 is formed by connecting anode to one terminal of primary winding 45 of the high voltage output transformer 45, the other terminal'of winding 46 being connected to the positive supply line 25. The plate circuits of control tube 500 are completed by connecting its anode 5%! through the dropping resistor 505 to the inter mediate positive supply line 44. Th grid circuit of control tube 500 is completed by connecting grid 502 to junction 33 of the output control resistor 55, the other terminal 65 of resistor being connected to the cathode 553 of tube 509, and to the negative supply line 35. The control system functions as follows: An increased output current in lines SI and l5 or 51 and 13 results in increased current flow in 56 and hence in an increased positive potential being applied to grid 552 of control tube 555. This results in an increase in the plate current flowing from 553! to 503 and. hence in an increased drop in resistor 505. Since the voltage between supply lines All and 30 is constant, this increased drop in has the effect of lowering the voltage across 55! and503. Since 55! and 553 are in series with the grid circuit of 305 and are connected as shown, this change has the efiect of decreasing the positive potential of grid 352. If tube 305 has been selected so that very little plate current flows at zero grid voltage but increases rapidly as becomes positive, then a small drop in positive potential of 302 will substantially reduce alternating current output of amplifier tube 330. In other words, tube 305 performs as a class C amplifier whose output is modulated by grid bias, the grid bias in this case being the control voltage from resistor 56.

Figure 20.This control system may be described generally as follows: It consists of a selfexcited oscillator 35, the amplitude of its oscillations being controlled by the plate voltage. The output of this oscillator is fed to a power amplifier whose output is then fed to the hi h voltage output transformer 45. The plate voltage ap plied to tube 35 is controlled so that as the load drawn through output control resistor 55 increases, the increased drop in this resistor makes the grid 502 of the auxiliary amplifier tube 5% become more positive; this allows more current to fiow from anode 5M to cathode 503, thus increasing the voltage drop in resistor 555, and thus reducin the plate voltage to tube 35.

The result is that increased load current tends to reduce the voltage output of oscillator tube 35 and conversely decreased load current tends to increase the oscillator tube voltage output.

In many respects the circuit of Figure 20 is very similar to that of Figure 19. In Figure 20 the selfexcited oscillator is the same as in Figure 19 except that its plate supply is variable, the plate circuit being completed by connection to one terminal of the plate winding 305, the opposite terminal of the winding 309 being connected to the dropping resistor 505. Resistor 555 is connected to the plate supply line 25. The junction of 555 and 399 is also connected to the anode 5d! of auxiliary tube 500, the cathode 503 of which is connected to the negative supply line 30. A capacitor 556 is connected between anode 553i and cathode 503, so that the plate potential of 500 will not vary at a high frequency rate but only at a rate sufiicient to control the plate voltage on 35 and hence the output of tube 35. The grid circuit of the auxiliary tube 500 is formed by connecting the grid 502 to the control resistor 56 at junction 33, the other end of 56, junction 60, is connected to plate supply terminal 30.

Referring to Figures 2 and 3, there is illustrateda physical embodiment of the power supply sys-- tem shown in the wiring diagram, Figure 1. It includes a relatively small base generally designated 8|, upon which there are mounted the voltage doubler tube H, oscillator tube 35, rectifier tube 50, a condenser pack generally designated 82 which contains condensers 25 and 21 and the high voltage transformer generally designated 45. For an apparatus having an output of 5 watts at 4,000 to 8,000 volts, the entire apparatus may be contained in a space having outer dimensions of, for example, 3 inches wide, 5 inches long, and 5 inches high, and weighing only about 2 pounds.

Variations in the mode of supplying power for the apparatus from varying sources are illustrated in Figures 4-10. One such variation is shown in Figure 4, the physical embodiment of this being shown in Figures 5 and 6. Another modification is illustrated by the Wiring diagram. Figure '7, and physical embodiment of this modification is described by Figures 8 and 9. A third modification is described with reference to the wiring diagram shown in Figure 10. These three modifications are identical with the ap aratus described by Figure 1 except that each modification represents a different tvpe of plate power supply, Each of these modifications will provide the same type of output and each has the same general advantages as described for the power supply of Figure 1, the only differences being that the three modifications offer a range of adaptability suitable for varying tvp s of electrical energy sources that may be available for the types of electron tubes used and for the amount of output power desired.

Any one of the types of oscillator controls described in Figures 1, 11 and 12-20 may also be applied to control the output of the invention as described by Figures 4, 7 and 10, the type used being determined largely by the type of tubes used and the amount of power output reouired.

Referring to Figure 4, there is illustrated a slightly modified form of the invention, wherein the oscillator 35, rectifier 55, and trans ormer 45 shown under the bracket 30, are identical with correspondingly numbered parts described and illustrated with reference to Figure 1. In Figure 4, however, the direct current supply for the oscillator tube 35, shown under the bracket 50 replaces the apparatus shown under the bracket l0 of Figure 1. Referring to Figure 4, the apparatus under the bracket includes alternating current feeders L1 and L2. At 02 there is illustrated a voltage doubler tube ha ing cathodes 93 and 94, indirectly heated by heaters 95 and 96, anode 91 which cooperates with cathode 93 and an anode 9B which cooperates with cat ode 94. A similar, preferably identical voltage doubler tube, is illustrated at if!!! and includes cathodes l0l and I02, which are indirectly heated by heaters 103 and HM. Cathode l ll' cooperates with an anode I05 and cathode 32 cooperates with an anode I05. Feeder L1 is connected directly to one terminal of a condenser I08 and thence through line I09 to one terminal of a condenser H2, thence through line H3 d1 is rectly to anode we ',of tube 100. iCat-hode :kfl comiected togjunction .1 14 on dine H 13. Anode :98 of tube :BZ-iys con ectedzthrou hllin Edi-directly tonunction M8 :on line :cathude -93 being-.connected to junction hi on line 9.9. Anode 18 t is connected through dine M5 to junction :Hfi n feeder L2. :Line is connected directly to 2-.QI1G terminal of condenser M1, :the other terminal 0f the =condenser being connected through dine 21;! .8 to one terminal :of scondenserdit, the .opposite terminal :of condenser dis being connected throu-gl1-line :lZ-l :togiunction #25 which seruesms one :of the output rter-minals 'of the direct lounrent voltage supply ior oscillator tube $5. athode M2 of tube :islikewiseconnecteddirectly to terminal J25.

iltrorn junction this ;on line [218 oi-rcuit rxtends through line L22 to :eathode ,9?! ref tube .412 and I from junction 4.23 :on dine 1-22 a cir.c.uit extends through line 'to :grid 3-9 ofloscillator tube 35. Anode lies of tube dill? @is leonnected directly to junction i26 on line i2 3.

Terminal 425 thus corresponds ,in iiunction to terminal #25 hi" the apparatus illustrated in Eligure 1. Junctionriiton feeder'ln servessasqone of the soutput terminals and corresponds in function torterrninal-dlleithe apparatuszshownr-infigure .1.

From junction |:3fi,'1i!18-3'2 extends to Junction 33 and (thence {through lline 43 to the-cathode andqgridiiii of theoscillator-ftube5. El e heater connection athrough tubes .412, we, 35, "and 350 in Figure a l, is similar to that --shown in Eigure -l,, exceptethatcathode l 5! .of tube :53 :igconneoted to heater 152 at junction 53. Ehus the heater :circuit c-extends l-froni -iunotion 283 on feeder L1 through line a8 1 rthrough l-heaters 295 and et :in series, line r8.3, heaters i133 :and J M inzseries, line 3 zheater 2L1, line 12, heater :52 :and line 2&7 Tto junction '33 and thence \throughline :32 to junction llxfi ondeederlc.

-Qscillator itube 135 includes cathode :36 indirectly heated-:byheater 3:1, grids 38, :an,d G9 and anode M. The half-wave rectifier tube :50 includes cathode :5! which is indirectly heated by heaters-i2 andsanranode 53. The transformer generally designated -45 includes ,a primary .46, 2a relatively-high voltage secpndary flia low-voltagesecondany 48 rand andron core :49. Junction 33 on.-line.$Z ,is connected 'by lline -54 :to junction 55 and thence :through voltage-regulating i resistor -56 and (condenser :5 l, Xin parallel, zto terminal 610 whichservesrasrin:B'igure -1, asi-a common-output terminal ,:to which ithe common output line (ii is :attached. Another output line 59 -.is connected :to junction 55. 1 One :end of :the winding 43 :is attached to terminal 60, the nther fiend being :connected :through :line .and {through grid bias :resistcr F4 rand :grid z-bias 'condenser r65, in parallel, "to the :control :grid "38 of the oscillator tube F35. One :"end of "t'he' primary -win'ding connected through line =to terminal i F25, the opposite end being connected through line 68 tothe anodell of'the'oscillator tubeh35. ll'circuit extends froni'the anode 53 of "the half-wave rectifier 5%, through line "TI to tap 112 on the high voltage winding .41. .Iap '72 may be Permanent or variable .as desired. .Ilhe .Qul osite end of iwinding A1, representedby ,terminallfi, serves 22,5 one .of .the rhigh .voltage output .terminals: of athe apparatus .to which output line .15 is rconnec-ted. -.A'-,tap '15 on lwinding t'l, zwhich likewise;maybesvariableronfixedzas.desired,"serves as another ihiBh noltage goutputiterminal (of the t6 apparatus and to which.iszconnectedou put 1-8.

Th appa tus illustra ed under the bracket 98 including tubes 92 and 10.0 with condensers W8, 1 l2, "HT and 120 serves -.to supply to termi! nals I25, and 13s a unidirectional voltage of approximately four times the crest value of the alternating current supplied to feeders L,1-and at no load. This -intermedia,te value unidirectional supplyadmirably serves as the input to standard oscillator tube 35,, which may thus operate lefiiciently.

A;physica1 embodiment of '.the apparatus, the Wiring diagram of which is illustrated in Figure {is shown in Figures 5 and 6. Thus, there illustrated a base member generally @designated l2! upon which there is mounted voltage doubler tubes ,92 and 100, the oscillator tube :35, :a 5111- denser -.pack I28, containing the condensers H18, I 22, =l-LT-and l 2 i), rectifier tube-: andahighwoltage transformer 45. Atypical apparatus pj-ithe type illustrated, capable of supplying 10 watts at from 8,000 to 16,000 volts, may be contained within a space 3 inches wide by 7 inches long by i'rinches high.

Referring to Figures 7, 8 and9,-.tl' 1ere is i-llustrated a modification,ofthe-apparatus ofitheinvention capable of being energized jrom a low voltage direct current source; for example, a storagebattery orsimilarlow voltagezsourcel such as might be available in portable-automotive vor aircraft installations. In the apparatus-of Eigure 7 the power supply for feeding the oscillator tube is illustrated under the bracket 190, the 10S- cillator tube transformer and recti-fier sections being illustrated under the bracket 180.

Low voltage power is supplied to lines 200 and 291. At ;-2 94 there is generally illustrated a.-'magnetically operated interrupter ;of the type ,customarily :used with automobile :radio apparatus. This apparatus may be of any approved design and consists generally of a magnetrcoil 1205 :Which serves :to-operatethe vibrator reed 206, the :reed 296 being provided with a wcontact member 12M which cooperates with contact 208 periodically to energize magnet 205 :and thus lseeptheweed 206 vibrating. The circuit through the-magnet 2&5 is from supply line?!) l junction 209, line'2 t0, magnet .295, line 2H "to contact '208 and thence through contact 201, line 2-I2,-juncti0n 213 and line :Z-M to junction 21.5 on supply line 200. Whenever power is supplied "to -lines 200.01 2M, the reed 1266 thus vibrates through the circuit intermittently established at the contacts :20!

, and not.

The vibration-of reed 2% serves to bring sit into contact vvitha pair of opposed contacts '2 I16 and =2 l-cl, .which-are connected respectively to opposite terminals of primary'win'ding 218 of the transformer generally designate'd'ZZil. "Themidpoint :of the "transformer winding H8 is connected through condenser -22| to terminal "-213, and is connected through line 2 E9 to feeder 20 l. Junction M3 is connected to rated 206 by "line 212 and to feeder 290 by line2 I54. Asthereed 2,116 vibrates, pulsatingdirect currentissupplied successively to alternate "halves of ,the transformer primary '2 i 8 and accordingly there is induced a higher voltage. alternatingcurrent in the trans former secondary winding 2.22. The terminals of secondary :winding 222 are comiected through lines 223 {and 2. 2 3 .to the anodes 225 and 2216, respectively, of the :full-wave (rectifier :tube .g,enorally designated 15230;, the mid ital 0i ithe see 17 ondary winding 222 being connected by line 22! to line 200.

The full-wave rectifier tube 230 is provided with a cathode 23! which is indirectly heated by heater 232, the latter being connected across the low voltage supply lines 200 and Cathode 23! is connected to line 261, which is connected through condenser 221 to feeder 200.

At 235 there is illustrated an oscillator tube which corresponds in function to oscillator tube of the apparatus illustrated in Figures 1 and 4. Oscillator tube 235 includes a cathode 236 which is indirectly heated by and connected to heater 231. Heater 231 is connected to supply lines 200 and 20!. Tube 235 includes control grid 238, a screen grid 239 and a suppressor grid 240 and anode 24!.

At 245 there is generally designated a transformer which corresponds in function to the transformer of the apparatus illustrated in Figures 1 and 4. The transformer 245 includes a primary winding 245, a high voltage secondary winding 241, a low voltage secondary winding 248 and an iron core 249 which is preferably of high grade thin transformer stock, the core of iron bein an incomplete magnetic circuit.

At 250 there is illustrated a half-wave rectifier tube having a cathode 25! which is indirectly heated by heater 252, the latter being connected directly across supply lines 200 and 20!. The cathode 25! is connected to supply line 206 as indicated at 258 and in this respect corresponds to the apparatus shown in Figure 4.

The connections of t e oscillator tube 235, transformer 245, and rectifier 250 are as follows: From junction 228 a circuit extends through dropping resistor 229 and through line 244 to grid 239 of tube 235, the condenser 254 being connected between line 244 and line 200. Line 261 runs from the cathode 23! of the rectifier tube 230 to one terminal of the primary winding 246 of transformer 245, the other terminal of the transformer winding being connected by line 268 to the anode 24! of the oscillator tube 235. A variable condenser 269 may be connected across the terminals of the transformer primary windin 246, as desired, for regulating the rate of oscillation of the oscillator tube 235, but in many instances the condenser 259 may be omitted since the inherent capacitance of the circuits is sufficient to sustain oscillation at a suitable frequency. One terminal of the low voltage transformer secondary winding 248 is connected at junction 260 to the output line 20i and is also connected through voltage regulating resistor 256 and voltage regulating condenser 251, in parallel, to junction 255 and thence through line 210 to the cathode 235 of the oscillator tube. From junction 255 a connection 243 extends to the suppressor grid 245 of the oscil lator tube. The opposite terminal of the low voltage secondary winding 248 is connected through line 263 and through the grid bias re sistor 254 with grid bias condenser 255 in parallel to the control grid 258 of the oscillator tube.

The high voltage secondary winding 241 of the transformer has an output terminal 213 connected to the output line 215 and another optionally variable output terminal 216 connected to the output line 218. A third terminal 219 is connected to the anode 253 of the rectifier tube 250. Another output line 259 is connected to supply line 200.

The voltage output of the full-wave rectifier 230 is supplied to the oscillator tube 245 and as explained with reference to the apparatus shown in Figures 1 and 4, the oscillator tube 235 oscillates at a rate as indicated with reference to Figure l, and so feeds the primary 245 of the iron or air core transformer 245, the construction of which depends upon the selected frequency of operation.

In Figures 8 and 9 there is illustrated a physical embodiment of the type of apparatus shown in Figure 7. In this apparatus there is illustrated a base generally designated 23E) upon which there is mounted transformer 220, a receptacle container for vibrating reed 204, a can 28! containing the several condensers used in the apparatus, oscillator tube 235, rectifier 230,

rectifier 250, and transformer 245. For an apparatus having a capacity of 30-40 watts output at 8,000-20,000 volts, the apparatus can be contained in a space 2-3 inches wide, 7-8 inches long and 5-7 inches high.

The apparatus illustrated in Figure 10 is a modification adapted to be energized from a low or intermediate voltage alternating current supply and includes transformer 285 having a primary winding 285 which is adapted to be connected to the low voltage alternating current supply lines L1 and L2. The transformer has a secondary 222, which corresponds to the secondary 222 of the apparatus shown in Figure 7, and a low voltage secondary 202 which is connected to the feeders 25! and 250. Otherwise the apparatus of Figure 10 is identical with that shown in Figure 7. The physical embodiment of the apparatus is approximately the same as that shown in Figure 9, except that the can 204 containing the vibrating reed is omitted and the apparatus may, therefore, be slightly rearranged so as to shorten the base.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments herein except as defined by the appended claims.

What I claim is:

1. A high voltage relatively low wattage power supply for precipitators, cathode ray oscilloscopes, X-ray machines and the like, adapted 10 be energized from a relatively low voltage power source, means for providing a direct current supply of intermediate voltage from said low voltage power source, a step-up transformer having a relatively low voltage primary and a high voltage secondary, a grid controlled oscillator tube having its input connected to the direct current supply of intermediate voltage and its output connected to the primary of said transformer, a rectifier connected to the secondary of said transformer, an ionization element connected to the rectifier output and a resistor connected in series with said ionization element and connected to said oscillator tube for varying the degree of oscillation of the tube in accordance with the ionization current flowing through the resistor, said apparatus being further characterized in that said means for providing a direct current of intermediate voltage includes a voltage doubler thermionic element connected to condenser bridge means.

2. A high voltage relatively low wattage power supply for precipitators, cathode ray oscilloscopes, X-ray machines and the like, adapted to be energized from a relatively low voltage power source, means for providing a direct current supply of intermediate voltage from said low voltage power source, a step-up transformer having a relatively low voltage primary and a high voltage fsecondary, a grid controlled oscillator tube hav- 'in'gits input connected to the direct current suprply of intermediate voltage and its output connected to the primary of said transformer, a rectifier connected to the secondary of said transformer, an ionization element connected to the rectifier output and a resistor connected in series with said ionization element and connected to said oscillator tube for varying the degree of oscillation of the tube in accordance withthe ionization current flowing through the resistor, said apparatus being further characterized in that said means for providing a direct current of intermediate voltage includes four thermionic cathode-anode valves and four storage condensers.

MORRIS NEWMAN,

20 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 1,979,422 Tholstrup Novrfi, 1934 2,051,372 Farnsworth Aug. 18, 1936 2,144,237 Wohlfarth Jan. 17, 1939 2,262,044 Philpott Nov. 11, 1941 2,302,876 Malling Nov. 24, 1942 2,306,888 Knick Dec. 29, 1942 2,386,548 Fogel Oct. 9, 1945 2,424,972 Dubin Aug. 5, 1947 2,444,349 Harrison June 29, 1948 

